Sonic well pump with critically tuned elastic support system and vibration isolator



2,902,937 TUNED ELASTIC SUPPORT Sept 8, .1959 A. 4cs. BoDlNE, .JR

SONIC WELL PUMP WITH CRITICALLY SYSTEM AND VIBRATION ISOLATOR Filed oct.22, 195e United States Patent O 2,902,937 SONIC WELL PUMP WHTHCRITICALLY TUNED ELASTIC SUPPORT SYSTEM AND VIBRATION ISOLATOR Albert G.Bodine, Jr., Van Nuys, Calif. Application Gctober 22, 1956, Serial No.617,413 1 Claim. (Cl. 10S-'76) This invention relates to sonic pumps ofthe general nature disclosed in my Patent No. 2,444,912, operating byperiodic Waves of compression and tension at sonic frequencies in anelastic column such as the pump tubing or a rod string, and the objectof the invention is the provision of improvements in such pumps in thedirection, first, of increased power utilization, and thereforeincreased pumping effort, for a given power unit, and second, ofisolation of the vibratory action in the pump tubing or rod string fromits stationary means of support at the ground surface.

In the aforementioned patent I disclosed several embodiments of the typeof sonic pump to which the present invention broadly pertains, includingforms in which the wave motion is transmitted down an elastic pumptubing, and other forms in which the wave motion is transmitted down anelastic rod string. Taking the first class as representative, theelastic tubing may typically be suspended from a spring-mounted platformat the ground surface, the spring means thereof being in turn borne bysuitable earth mounted support means. A vibration igenerator oroscillator such as an eccentrically weighted flywheel combination ismounted in bearings supported on the platform in a housing which ismounted atop the tubing, and serves, when driven at high rotationalvelocity, to supply a vertical oscillatory force which longitudinallyreciprocates the upper end of the tubing through a short displacementdistance in such a manner as to transmit down it alternate deformationwaves of tension and compression. Points along the tubing are thus setinto vertical oscillation. Preferably, the Waves are generated at such afrequency relative to the length of the tubing that the tubing isresonated and there is produced therein, in a manner well known to thosefamiliar with the acoustic art, a standing wave characterized byalternate nodal and anti-nodal regions of minimum and maximumoscillatory movement. lOne or more fluid impelling and check valve unitsare mounted in the tubing, preferably at points of maximum oscillatorymovement (velocity anti-nodes), so as to participate in the verticaloscillation of the portions of the tubing in which they are mounted,whereby increments of uid are pumped upwardly past the check valves tobe elevated in the tubing.

Considering the operation of such a pumping system under idealizedconditions, with the assumption of an operating frequency whichresonates the tubing, and with the mass, or mass reactance, of theoscillator at lirst neglected, a velocity anti-node occurs at the upperend of the tubing, at the point where the oscillator is mounted thereon,and a first node, or stress anti-node, occurs at a spacing distanceone-quarter wavelength down the down the tubing from its upper end. Thevibratory tubing system in such assumed state would be ideally preparedfor eflicient, maximum amplitude drive by the oscillator. However, inpractice, the considerable mass of the oscillator unfavorably modiiiesthe wave action in the tubing. Acting as a terminating untuned massreactance, its effect is to reduce the distance down the tubing to therst stress anti-node to considerably less than a quarter Wavelength, andat the same time to correspondingly reduce the oscillation amplitude ofthe tubing at its upper end, i.e., at the velocity anti-node.

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Thus, while a maximized rst stress anti-node is attained, less than amaximized velocity anti-node is attained at the upper end, and powerinput into the tubing suffers accordingly.

I have discovered that maximized oscillation amplitude may be attainedat the upper end of the tuning for a given oscillator and and a givenstress maxima at the first stress anti-node by critically tuning theelastic oscillatory system consisting of the oscillator and the springmounting for the tubing to the operating frequency of the oscillator.With such tuning, the mass reactance of the oscillator is balanced bythe stiffness or elasticity reactance, and a full amplitude velocityantinode is secured at the upper end of the tubing. |This is accompaniedby a downward shift of the irst stress anti-node to a full quarterwavelength below the upper end of the tubing. This oscillatory forceexerted by the oscillator on the upper end of the tubing then actsthroughout a longer stroke, with consequent increased power flow intothe tubing.

I have further discovered that by critically tuning the elasticallyvibratory system consisting of the oscillator and the spring support forthe tubing to resonate at the oscillation frequency of the oscillator, Ieffectively isolate the entire vibratory pump system from its stationarysupport means at the ground surface. This has several importantadvantages, including conservation of the vibratory energy delivered bythe oscillator, elimination of undesirable Vibration in theground-mounted support means for the spring-mounted tubing supportplatform, and avoidance of opposition to free oscillation of the pumpsystem by the tubing support means.

The phenomena referred to in the preceding paragraph fcan be betterappreciated by use of the concept of mechanical impedance, which is theratio of cyclic peak force acting at any given point in an elasticallyvibrating system to displacement velocity at that point in the system. Avelocity anti-node region is a region of low mechanical impedance. Theupper end of the pump tubing, where supported by the spring-mountedplatform, is accordingly a region of low mechanical impedance; and itwill be seen that the greater the stroke, the greater will be thedisplacement velocity, and therefore the lower will be the mechanicalimpedance. The ground supported mounting for the spring support meansthat carries the tubing is so constructed as to be a region of highmechanical impedance. It will be seen that the steadier or morestationary this mounting can be made to stand, the higher will be themechanical impedance at this point. It will be evident that a highimpedance at this point denotes minimization of transmission ofvibratory energy into this mounting and to the ground, giving theadvantage of conservation of vibratory energy, as well as absence ofundesirable shaking of the mounting and the surrounding ground area. Itwill further be evident that a low impedance at the point of support ofthe tubing by the spring-mounted platform minimizes blocking impedanceto free vibration of the upper end portion of the tubing. These desiredimpedance conditions are obtained, in accordance with the invention, bythe above described critical tuning of the elastic vibratory systemconsisting of oscillator and spring support means to the frequency ofoperation of the oscillator, together with the provision of a steady orrigid mounting for said spring support means.

summarizing, the described critical tuning of the oscillator and springsupport means for the tubing raises power inflow into the tubing, and bycombining therewith a high impedance point of support for said springsupport means, there is further accomplished minimized leakage ofvibratory energy from the system, minimized shaking of the groundsupported mounting for the equipment, and mini.-

Patented Sept. 8, 1959 f tubing by the spring support means.

The invention will be better understood by referring now to thefollowing. detailed description of an illustrative embodiment of theinvention, reference being'hadl to the accompanying drawings, in which:

Fig. l is a longitudinal sectional view of the upper end portion ofr asonic well pump in accordance with` the inventijon;

Fig. 2 shows the lower end portion of the pump tube; and

Pigs. 3 and' 4 are diagrams. of sonic pumps and their Wavecharacteristics, with and without, respecitvely, the provisions of thepresent invention.

In the drawings an illustrative sonic oil well pumping installation isshowin, the well bore being shown to be lined part way down by surfacecasing 10,.while annularly spaced inside casing is production casing 11,perforated at its lower end, as at 11a, and inside of which has beensuspended the elastic steel. pump tubing 12. Mounted at the top ofcasings 10 and 11 is a suitable casing head 13, and the pump tubing 12extends upwardly through the casing head and has mounted at its upperend `a vibration generator or oscillator G. This generator G'. comprisesa. housing 16 containing a device for vibrating the upper end of thetubing 12 in a direction longitudinally of the latter, thereby exertinga vertical oscillatoryforce upon the upper end of the tube.

' The means for generating the vibratory action is here shown of asimple type embodying meshingl oppositely rotating spur gears 17`carrying eccentric weights 18 which balance. out horizontal vibrationsbut act additively to produce a substantial resultant oscillatory forcein a vertical direction. The generator has a` driving pulley 19 driventhrough belt 20 from electric drive motor 2,1. Since this vibrator isemployed to generate elastic waves of tension and compression in thepumpA tubing which are of the. sameY nature as sound waves and travelwith the speed of sound in the. pipe, I may properly refer to thisvibrator as a sonic wave generator.

Extending upwardly from casing head 13, at an annular spacing outsidetubing string 12, is a short and relatively sti pipe section 24, andmountedv on the upper end ofthe latter is a supporting head having. atthe topA a ange 26. Bolted to ange 26 is a ange 27 of a tubular fitting28. on the bottom of a relatively heavy stationary lower platform 29 forthe spring support device 30 for the tubing string and vibrationgenerator G, the tubing being packed by a stuing -box at 29a. The largediameter outer casing 10, cemented in the well, as indicated at 10a,together with casing head 13, pipe 12, tting 25, and the relativelymassive platform 29, constitute in this case the ground supportedmounting means for the spring support device 30. The platform 29 andsystem on which it is mounted constitute a considerable mass, andthepipe section 24 and casing 10, down to the support of thecasing,constitutes a high elastic stiffness. The platform 29 hence has highinertial properties, and provides a rm high impedance base for supportdevice 30.

Spring support device 30 includes an upper plate or platform 31,supported from lower platform 29 by a plurality of coil springs 32,vertical guide rods 33 being used inside these coil springs, and theserods will be understood to be set tightly into lower platform 29- andto` pass freely through apertures in platform 31. A collar 35 near theupper end of the tubing string overhangs an upwardly facing seatingshoulder 36 formed in the member 31, and it will be understood that theweight of the tubing string and vibrator G are transferred to theVmember 31 and, through springs 32, to the rigid platform 29. Y

A fitting 40 at the top end of the pump tubing, between the tubing andgenerator:V G, delivers production fluid to delivery line 41.

vAs is disclosed in my aforementionedV Patent No. 2;.444,912the pumptubing contains one, or more llid impelling assemblies, in theillustrative case, including check valves, such as indicated at C, andsuch valves may comprise a tubular fluid displacing member 50 mounted inthe tubing string, preferably at the calculated location of a velocityanti-node of the wave set up in the tubing, and a check valve element 52seating at the top end of the fluid passage 53 through the member 50. Insome instances the valve element 52 is urged -towards its seat by abiasing spring 54.

Theessential operation of such a pump is fully set forth in myaforementioned patent. Briefly, operation is as follows: It will berecalled that periodic deformation waves of tension and compressiontravel down the pump tubing as a result, of the vertical oscillatingforce applied to the upper end thereof by theY generator G. These wavesset localvelocity anti-node regions of the tubing into verticaloscillationV through an amplitude up to say 1/z inch. 'Ihe tubular valvemembers 50 accordingly have this vertical oscillation. Oneachdownstroke, the member 50 travels with an acceleration suflicient toseparate from the valve element 52, and fluidY displacing by member 5,0travels upwardly therethrough and past the then unseated valve element52. On the upstroke, valve element 52 seats, andthe column of welluidthereabovc is elevated. The columnof well fluid above the4 valve element52 does not substantially drop during theV downstroke, because theacceleration of the parts onv the down-stroke, considerably exceeds theVacceleration of gravity.,

In accordancefwith, the present invention, the vibratory systemconsisting of oscillator or generator G, the platform 31 and `thesupportingl springs 32 is critically tuned to resonate at thev frequencyofV operation of generator G. Thisas willbe readily appreciated by thoseskilled in the art, may be accomplished by giving the components of thelsystem the proper mass and elasticity properties` to satisfy the..equation k frn n in which m is the equivalent vibratory mass of theseveral vibrating components, k is the spring constant, and f is thefrequency for resonance. In the preferred practice of the invention, thegenerator G is operated at a frequency to resonate the pump tubing,establishnig fixed nodal and. anti-nodal regions as heretoforeexplained.

The. elastically oscillatory system consisting of the generator,platform 31 and springs 32- is thenltuned, asex plained, tothispredetermined operating frequency of the generator G.

Reference to the diagrams of Figs. 3 and 4 willV make clear the improvedperformance accomplished by the invention. Fig, 3; depicts a sonic pumpwith an untuned elastic, support system, and at w1 is represented thecorresponding Standing wave in the tubing. A velocity antinodeV1roccurs' at the upper endofthe tubing, where supported by platform 31.The rst stressl anti-node S1 is shown at a; considerable levelabove aquarter wavelength distance down-the tubing, and the velocity andstressanti.- nodes V2,V S2, V3, etc., are spaced below stress anti-nodeS1 at normal quarter waveA intervals. The oscillation displacementamplitude atvelocity anti-node V1, at the upper end of the tube, isrepresented on wave. w1 at d. The completion of the upper quarterwavelength of the standing wave w1 above the levelof V1, is indicated inphantom lines, and at da is indicated the theoretical displacementamplitude that would occur at the upper end portion of the tubing at V1,if it were not for the upward shift of the wave pattern. It will beunderstood from the foregoing that the reason for the illustrated upwardshift or displacement of 'wave pattern w1, with first stress anti'- nodeS1 located at considerably less than a quarter wavelength down thetubingfrom its upper end, has resulted fromy the untuned mass of oscillator G,platform 31, andthe springs 32. It will be evident that theactualIoscillation displacement d asa consequence of the conditions describedis materially less than the maximum displacement do that would beavailable were it not for the high position (substantially less than aquarter wavelength from the top) of the iirst stress anti-node.

Fig. 4 shows the performance attained when the vibratory systemconsisting of the oscillator G, platform 31 and springs 32 is criticallytuned to resonate at the frequency of operation of oscillator G. In thiscase, the first stress anti-node S1 is a full quarter wavelength downthe tubing from the top, and the resulting standing wave is asrepresented, with the maximum oscillation amplitude d1 obtained at thetop end of the tubing. It is thus seen that the described tuning resultsin maximized oscillation amplitude at the upper end of the tubing, andit will be appreciated from what has gone before that this results inmaximized power ow from the generator into the tubing. To repeat whathas previously been stated, a given oscillating force applied by thegenerator to the upper end of the tubing now acts throughout a greaterdisplacement distance, Which directly translates into correspondinglyincreased power transmission into the tubing. Looked at somewhatdifferently, because of the high upper node S1 in the case of Figure 3,caused by the untuned mass of the oscillator on the upper end of thepipe 12, the oscillator is forced to drive the pipe 12 at acomparatively high impedance region thereof, i.e., at a pointundesirably close to the node. It must be realized that the pipe cannotbe driven at all at a node, which is a point of very high impedance; ismost effectively driven at an antinode, which is a point of minimumimpedance; and the closer the point of drive to the node, the greater isthe impedance of the pipe at the drive point, and the greater theapplied oscillatory force must therefore be to attain a given vibrationamplitude at the velocity antinodes V2, V3, etc., along the pipe. Hence,a given oscillator having a given effective unbalanced drive forceweight, connected in the prior art system of Figure 3, so as to attainthe vibration amplitude represented at the velocity antinodes V2 and V3,can be replaced in the system of Figure 4 by an oscillator havingsmaller unbalanced drive force, without reduction of the vibrationamplitude at the nodes V2 and V3. Or, using the same oscillator,increased vibration amplitude would be realized at the antinodes in thecase of Figure 4. The explanation of these phenomena is that,considering the over-all vibration system as a whole, the effective massreactance of the oscillator is tuned out of the system by selecting thesprings 32 such that the spring reactance is equated to this massreactance at the operating frequency. The mass reactance of theoscillator being thus reduced to zero, the pipe 12 vibrates as in Figure4, as though the entire effective mass loading of the oscillator on thepipe had been removed; and in consequence, the upper node S1 drops to afull quarter-wave-length distance down from the top end of the pipe, andthe vibration amplitude at the top, for a given oscillator, increasesfrom d to d1. The concept of tuning the springs 32 to the `mass of theoscillator at the frequency of vibration of the oscillator and pipe isalso applicable in case the pipe is not vibrated at resonance, and doesnot therefore exhibit a standing wave pattern, in that, in such casealso, it is an important improvement to achieve a low impedance outputfrom the oscillator (maximized amplitude of oscillation), so thatmaximized wave energy is delivered to the pipe. It will be evident thatby tuning the springs 32 to the effective mass of the oscillator, asecondary vibratory system is provided which is a part of the over-allvibratory system, and which is resonant at the operating frequencywhether or not standing wave resonance is established in the pipe. Thebenefit gained has been found in practice to be very material andimportant.

As explained earlier herein, the velocity anti-anode region V1 of the,tubing is a region of low mechanical impedance, while the support pointfor the springs 32, consisting in this case of the firmly mountedplatfOl'm 29,

is a region of high mechanical impedance. yIt Will be clear from aconsideration of Fig. 1 that vibration transmission from the tubingthrough the springs 32 to the platform 29, and from the latter down thesupporting pipe 24 to the casing head, and thence through casing 10 tothe earth, would be a highly undesirable condition. It should further beevident that, aside from the mere problem of undesired shaking, any suchvibration transmission represents a power leak from the vibratorysystem. It should further be clear that any impedance 0ffered to thevibratory tubing 12 by the spring supporting system is highlyundesirable. All these conditions are taken care of by the describedcritical tuning of the elastically vibratory system consisting ofgenerator G, platform 31 and the springs 32, combined with a firm orsolid base for said springs. These conditions being met, a low impedanceexists at the coupling point between tubing and spring supportedplatform 31, a high irnpedance exists at the spring supporting platform29, and all of the foregoing objectives of the invention are attained.

The invention has now been disclosed in one specific illustrative form.It will be understood, however, that the embodiment illustrated isillustrative only, and various changes are within the scope of theinventions. It will further be understood that the invention is notlimited in application to sonic pumps in which the vibratory column is apump tubing, but is equally applicable, as will readily be recognized bythose skilled in the art, to sonic pumps in which the vibratory columnis a rod string inside the tubing, as particularly shown in my PatentNo. 2,553,541.

I claim:

A deep well pump which comprises: a fluid impelling means positioned inthe well, a wave transmitting elastic column extending from the groundsurface to said iiuid impelling means and operatively connected thereto,a mechanical oscillator for exerting an oscillatory force on the upperend of said elastic column at a predetermined frequency, said oscillatorhaving oscillatory force means operable at said predetermined frequency,and said force means being connected to said column in forcetransmitting relationship, and an oscillatory spring support means forsupporting said column near the point of said connection of saidoscillator, including a firm supporting base, means on said columnadjacent said point of said connection, and spring means connectedbetween said base and said means on said column, said column, oscillatorand oscillatory spring support means constituting an over-all vibratorysystem, and said spring means being tuned so as to have a springconstant so related to the combined eiective oscillating mass of theoscillatory spring support means and oscillator that the portion of saidover-all vibratory system composed of said oscillatory spring supportmeans and oscillator comprises a secondary oscillatory system which hasa resonance at said predetermined frequency, such that the massreactance in the over-all vibratory system oiered by said mechanicaloscillator and said support means is vectorially opposed andcounterbalanced by the stiffness reactance of said spring means, andmaximized output force applied through maximized oscillation amplitudedistance is thereby exerted by said oscillator on said column, and allin such manner that said spring support means olers minimized impedanceto said wave transmitting elastic column, and said supporting baseoffers maximized impedance to said oscillatory spring support means,whereby vibrational energy is substantially confined against leakagethrough said supporting base, and said spring support means presentsminimal blocking impedance to said wave transmitting elastic column.

References Cited in the file of this patent UNITED STATES PATENTS2,444,912 Bodine July 13, 1948 2,553,541 Bodine May 22, 1951 2,572,977Bodine Oct. 30, 1951

